Analytical Electron Microscopy: A multiple-tool technique for …maud/Maud2015/AEM_Gialanella.pdf · Dipartimento di Ingegneria Industriale Università di Trento MAUD - Trento 2015

Analytical Electron Microscopy:

A multiple-tool technique for combined analysis

Stefano Gialanella

Dipartimento di Ingegneria Industriale

Dipartimento di Ingegneria IndustrialeUniversità di Trento

MAUD - Trento2015


MAUD - Trento2015


MAUD - Trento2015

Outline: • Analytical Electron Microscopy • Electron Diffraction

Selected area electron diffraction (SAED) Convergent beam electron diffraction (CBED) Kikuchi lines

•  Imaging Diffraction contrast Applications Bright Field – Dark Field

•  Spectroscopies Energy Dispersive X-Ray Spectroscopy (EDXS) Electron Energy Loss Spectroscopy (EELS)


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MAUD - Trento2015

Analytical Electron Microscopy


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IMAGING MICROSTRUCTURE

DIFFRACTION CRYSTALLINE STRUCTURE

SPECTROSCOPIES COMPOSITION



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Bright Field

Dark Field


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Bright Field

Dark Field SAED


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Incoming beam

Specimen

Trace of the SAED aperture

Transmitted beam

Diffracted beam Plate

Electron Diffraction Selected Area Electron Diffraction (SAED)

Basics


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Electron Diffraction SAED

The patterns


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Spot pattern

Ring pattern


The patterns


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Electron Diffraction SAED The patterns


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1g2g

2g

1g

B

Plate

B = g 1 × g 2 =

=B Beam direction

Zone axis

Sample orientation



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2,0,-2

2,-1,-1

2,-2,0

1,1,-2

1,0,-1

1,-1,0

1,-2,1

0,2,-2

0,1,-1

0,-1,1

0,-2,2

-1,2,-1

-1,1,0

-1,0,1

-1,-1,2

-2,2,0

-2,1,1

-2,0,2

a*b*

c*

Zone axis : [1,1,1]

•  1 -1 0

•  Ex.: g1 = [110] g2 = [101] zone axis = 1 0 -1 = [111]

• 

Sample orientation



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Convergent beam electron diffraction (CBED) Electron Diffraction


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Kikuchi lines Electron Diffraction


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Diffraction contrast: defect investigation

Diffraction contrast Imaging Applications


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MAUD - Trento2015



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Diffraction contrast Imaging Bright Field – Dark Field


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Dolcet et al.:Eur. J. Inorg. Chem. 2015, 706–714

C- ZnS H- ZnO


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Energy Dispersive X-ray Spectroscopy (EDXS) Spectroscopies X-ray formation


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Spectroscopies

TEM. A Textbook for Materials Science, 2nd ed. William & Carter (2006)

EDXS

TEM-EDXS Interface


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Spectroscopies EDXS

TEM-EDXS Interface

Courtesy N.J. Zaluzec.


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Spectroscopies EDXS

EDXS Detectors

Si(Li)

LN2 cold finger



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Spectroscopies EDXS

EDXS Detectors

Si Drift Detector



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Spectroscopies EDXS

EDXS Detectors

Si Drift Detector



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Spectroscopies EDXS

EDXS Detectors



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Spectroscopies EDXS

Spatial resolution & electron interaction volume

•  Spatial resolution increases with electron energy

•  Interaction volume extremely limited •  Low count rates

•  High resolution TEM T

EM

SE

M


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Spectroscopies EDXS

Qualitative analysis


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Spectroscopies EDXS



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Spectroscopies EDXS



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Spectroscopies EDXS



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Spectroscopies EDXS


I e II: BSEIII: SE


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Spectroscopies EDXS Qualitative analysis


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Silicon X-ray escape peaks

Silicon internal fluorescence peak

Spectroscopies EDXS Spuroius peaks - Detector


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Spectroscopies EDXS

Silicon internal fluorescence peak

Spuroius peaks - Detector


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Pile-up peaks

Spectroscopies EDXS Spuroius peaks - Detector


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Spectroscopies EDXS

Spurious signals - Microscope


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Spectroscopies EDXS

The Hole Count




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Spectroscopies EDXS




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Spectroscopies EDXS




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Spectroscopies EDXS Spurious signals – Sample Holder

!

!

!TiO2 -Au

Cu & Zn lines from sample holder


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Spectroscopies EDXS

Extra signals

Reese, GM, Spence, JCH and Yamamoto,N.; Coherent Bremsstrahlung from Kilovolt Electrons in Zone Axis Orientations Phil. Mag. A 49 697–716 (1984).


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Spectroscopies

Instrumental parameters:

Channel width: 10 eV/ch or better

Time constant: generally better low values to maximise count rate

Multichannel energy resolution: to be periodically checked.

EDXS

Test strategy

Critical parameters:

Spectrometer resolution

Calibration of the energy range

Maximum output count rate


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Ci

Ci,STD

= KIi

Ii ,STD

Spectroscopies EDXS

Quantitative analysis


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K, for bulk/thick samples depends on: Z - Atomic number A -X-ray absorption F - X-ray secondary fluorescence

Thin sample(foil) criterion: - “Matrix effect” is not so imporant, as interaction volume is very small.

- Absorption and fluorescence can be disregarded.

Spectroscopies EDXS



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CA

CB

= KAB

IA

IB

CLIFF-LORIMER equation:

Spectroscopies EDXS

EDXS quantitative analysis is usually quite straightforward in a TEM (thin-film approximation)



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Spectroscopies

How to decide if the above approximationis valid!? When the bremsstralung X-rays are not absorbed in the specimen.

EDXS



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Spectroscopies

Step by step quantitative analysis – Standard approach 1.  Verify thin sample approximation

2.  Acquire standard sample spectrum/a

3.  Measure IA, IB, IC,….

4.  Evaluate KAB, KBC, …

5.  Acquire sample spectrum/a

6.  Measure IA, IB, IC,…

7.  Evaluate CA,CB, CC,… TEM. A Textbook for Materials Scince, 2nd ed. William & Carter (2006)

EDXS Quantitative analysis


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KAB =KAC

KBC

Spectroscopies

CA

CB

= KAB

IA

IB

EDXS


CA

CC

= KAC

IA

IC

CB

CC

= KBC

IB

IC

IA + IB + IC =100


MAUD - Trento2015 TEM. A Textbook for Materials Science, 2nd ed. William & Carter (2006)

1)  Experimental determination, using standard samples Time spending

More accurate results

2)  First principles calculation

Quick Less reliable results

Spectroscopies EDXS

Determination of KAB


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•  Inelastic interaction “products”

- Interband transitions (few eV) - Plasmons (10 eV) - Phonons (10-2 eV) - Core electron excitation

Characteristic X-rays (E>102 eV up to E>104 eV) Energy loss electrons (102 eV (range) < E <104 eV (range))

Spectroscopies Electron Energy-Loss Spectroscopy (EELS)

EELS – vs - EDXS


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Spectroscopies EELS

EELS – vs - EDXS


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Spectroscopies EELS

Instrumentation


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Spectroscopies Spectroscopies EELS

Instrumentation


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- Zero-loss peak

- Plasmon peak(s)

- Absorption edges

Spectroscopies EELS

Spectrum components


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Spectroscopies EELS

Quantification


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Spectroscopies EELS

Fine structure


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10 nm

Plate-like precipitate in a Al-Cu-Ag-Mg alloy

Spectroscopies EELS

Imaging & mapping


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10 nm

Spectroscopies EELS Imaging & mapping


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Essential Bibliography

1- G. Thomas, M. J. Goringe - Transmission Electron Microscopy of Materials, Wiley publ. (1979).

2- D. B. Williams, C. B. Carter - Transmission Electron Microscopy: A Textbook for Materials Science,

Plenum Press New York (1996) or 2nd ed (2006).

3- B. Fultz, J. Howe, Transmission electron microscopy and diffractometry of materials, 2nd or 3rd ed., Springer (2002)

4- P. J. Goodhew - Thin Foil Preparation for Electron Microscopy, in Practical Methods in Electron Microscopy,

Ed. Audrey M. Glauert, Elsevier publ. (1985).

5- J. W. Edington - Practical Electron Microscopy in Materials Science, Philips Tech. Library (1974).

6- P.B. Hirsch, A. Howie, R. B. Nicholson, D. W. Pashley, M. J. Whelan - Electron Microscopy of Thin Crystal,

2nd ed.,Kreiger Huntingdone publ. (1977).

7- Handbook of Microscopy Applications in Materials Science Solid-State Physics and Chemistry –

Applications,Ed. S. Amelinckx, D. van Dyck, J. van Landuyt, G. van Tendeloo, VCH (1998).

8- L. Reimer - Transmission Electron Microscopy, 2nd ed., Springer-Verlag (1989).

9- Principles of Analytical Electron Microscopy, Ed. D.C. Joy, A.D. Romig, J.I. Goldstein, Plenum Press (1986).

10- J.C.H. Spence - Experimental High-Resolution Microscopy, Oxford Univ. Press (1988).

11- R.F. Egerton – Electron Energy-Loss Spectroscopy in the Electron Microscope, Plenum Press (1996).

Documents

Analytical Electron Microscopy: A multiple-tool technique for …maud/Maud2015/AEM_Gialanella.pdf · Dipartimento di Ingegneria Industriale Università di Trento MAUD - Trento 2015